-LRB- CNN -RRB- -- Memorial Day weekend has , over the years , turned in large part into something it was not originally intended to be :

Seventy-two hours of barbecues and ballgames , of swimming-pool openings , of high-decibel sales pitches by merchandisers hoping to cash in on the unofficial start of summer .

Which , to a degree , is understandable . The weather is turning warm , there 's a holiday feel to the break from work , and the solemnity and grieving for those who gave their lives in the pursuit of peace seems to sometimes get pushed aside .

But it is that pursuit of peace , with all its contradictions and all its sacrifices , that remains the centerpiece of Memorial Day .

And this weekend it might be worth pausing , if only for a moment , to reflect upon a quotation that has variously been attributed to Winston Churchill and to George Orwell :

`` We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm . ''

Through history , peace in the world has often , of necessity , been attained by the most brutal means available during military conflict . There is a dichotomy intrinsic to wars waged in pursuit of peace -- an uneasy divide between lightness and shadows . Tranquility born of bloodshed ; happiness the end result of horror . We do n't like to think too much about that , and no wonder . The truth behind it goes against our better nature .

What is the most beloved image celebrating the joyous end of World War II ?

It 's the Alfred Eisenstaedt photo of the sailor and the nurse embracing in Times Square . Even now , more than 60 years later , that photo makes people weep with glad emotion , makes them grin with across-the-generations exultation . That photo , it is often declared , says it all .

But there would be no photo of the sailor and the nurse were it not for scenes no one likes to see in photographs : the atomic bombing of Hiroshima and Nagasaki that brought the awful years of war to a close . It is perfectly explicable that we much prefer bathing ourselves in exuberant images of the first hours of peace , rather than the gruesome images of the last hours of war .

One person who was in fact present during those last hours of World War II was Paul Tibbets . During the many days and evenings I spent with him during the final years of his life , there were occasions when the conversation would turn to that photo of the sailor and the nurse . Sometimes , when we were traveling together and he would be attending a military reunion , someone would approach him with a copy of the photo .

Paul would never say anything . He 'd look over at me and merely raise his eyebrows , almost imperceptibly . He was n't the photographer , but Eisenstaedt would have had nothing to photograph were it not for him .

He was the man -- the military aviator -- assigned by the United States government to put together , in utter secrecy , the unit that would carry out the atomic raids on Japan . When the day came , he did n't delegate ; he flew the B-29 named Enola Gay -- his mother 's name -- to Hiroshima with one goal in mind : to make the war stop . To let the soldiers , sailors , aviators and Marines go home at last , to rejoin their families or start new families , to somehow , after all the suffering and all the heartbreak , find peace .

Of course the sailor and the nurse are the preferred visual representation of victory . What Paul Tibbets , navigator Dutch Van Kirk , bombardier Tom Ferebee and their crew were asked to do over the skies of Japan is something that is difficult for many people to think about ; it 's much more pleasant to smile at the sight of the kiss in New York .

Peace is the sun-dappled result , but getting there can be a path of darkness upon darkness . Which is why , on Memorial Day weekend , it is probably reasonable that some people reflexively turn away from thoughts of battlefields and death . The people who turn away are generally not the ones whose family members have in wartime trod that dark and lonely path .

On the occasions through the centuries when long wars have come to an end , many newspapers have chosen to go with the most glorious single-word , all-capital-letters headline of all :

PEACE !

Is there a word in the English language that is more welcome , more highly cherished ? That is more likely to be greeted with exhilaration and prayerful relief by all who see it ? Nearly every desire a person , or a nation , can have is embodied in that single syllable .

All the lightness and all the shadows , all the wars waged at terrible costs , all in pursuit of peace . To get to such a state of harmony has never been a peaceful journey .

Which is why the word is so beautiful , so yearned for :

Because it sounds so simple while remaining so rare .

The opinions expressed in this commentary are solely those of Bob Greene .

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Bob Greene : Memorial Day a holiday for barbecues , fun ; but better to reflect on peace

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He says day raises dichotomy : brutality , which we shun , to bring peace , which we embrace

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His friend dropped Hiroshima bomb from Enola Gay . His purpose to end war , bring peace

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Greene : We prefer to think of war 's end in famous V-J day kiss photo